Disappearing coolant after overheating = blown head gasket?
 

Hi all. Thank you for an excellent site.
I'll be as succinct as possible...

Car:1998 318ti, 130,000 mi.
Engine: M44, BMW-rebuilt long block, 60,000 mi.
I've owned the car for the past 70,000 mi / 5 years.

1. I have read about others having a problem with no heat at idle.
I had this all the time I've owned the car, never thought much of it (I don't tend to use the car for stake-outs). It's better after bleeding.

2. Car has always seemed to have a slow coolant leak. Every now and then, I've had to put some more in - not often enough to recognize a pattern, and the temp never went above the middle line.

3. 2 weeks ago, I was snowblowing the driveway, moved the car to clear its space, left it idling with the lights on, so I could see (gets dark before 4), found the temp needle pinned when I got back to it after 20 minutes.

4. Like an idiot, had an irresistible urge to open the cap - after parking car and turning off, slowly loosened cap, allowing pressure to bleed off, then removed cap - Look, Ma, no coolant!

5. Filled with coolant when cool - put in as much as it would take.

6. Next morning, set off for work (ambient temp ~5F), car warmed up as usual, then just kept on going - needle buried in red after about 3 miles. Heat never came on. Stopped car, sat, waited. Scraped ice from inside of windows. At normal temp, restarted, headed home. Temp increased, went into red, stopped about 1/2 way into red and stayed there, drove home very slowly like that. Car stalled when I put in clutch going into driveway (creating perfect cork in 4 foot high snowplow mound). Took 256,000-mile diesel pickup to work.

7. Surfed internet at work, found out about little bleeder screw.
Went home, confirmed NO MENTION of little bleeder screw in owner's manual (in fact, it's even AIRBRUSHED OUT in the coolant filler picture). Got angry.

8. Refilled with 50:50 BMW antifreeze, bled air from little bleeder valve.
Repeated a few times after driving (found out little bleeder valve can be opened and closed with a quarter).

9. No more overheating, either driving or at idle, and heat came on sooner.

10. Then it didn't. Added more fluid. Then added more again. And again. Can easily add 1/2 gallon after 20 or so miles.

11. No steam from exhaust, no smell of coolant, no coolant puddles (never were).
Radiator smells of exhaust when you open it.
Compression, cyls 1 to 4, in psi: 180 140 170 190
#2 plug slightly oily, others normal, and about the same as each other.

Questions:
- Does all of this seem to add up to any specific pattern (head gasket, cracked head / block, imminent nuclear annihilation, etc)?
- I don't have a garage, and am not pulling the head in the snow in January in Maine. Is it okay to drive it like this, adding coolant daily, until the spring (like May) when I can finally work outdoors around here?
- Any other words of wisdom or humiliation?

ps: I'm a 45 year old guy who has owned and rebuilt LOTS of cars.
Little bleeder screw not mentioned in owner's manual.
I've never yet read a service manual before putting water into a car.
Little bleeder screw is matte black plastic on a matte black plastic background with the German word for "bleeder" embossed UPSiDE DOWN in tiny letters in black plastic around screw.
Am I an idiot? (you know what I want to hear...)

I'd say headgasket if there's oil on the #2 plug and the #2 cylinder has lower compression

The cooling system is pretty much a sealed system and that is probably why not much is mentioned in the owner's manual. Sometimes you need to bleed the system a couple times.

Not sure, but did you have the heat one when you bled it?

Oil looks good?

Hrm, sounds like a headgasket job from the compression results. You said the plugs were good, are you sure the two center plugs were normal and not white from igniting fuel with coolant? From a dead cold, you should be able to start the engine with the radiator cap off and have the coolant just sit there, if its moving at all, the headgasket is definately gone or youve cracked the head at some point. Another thing, though youd smell, is the coolant line at the rear of head that tends to break fairly easily by itself causing a slow or rapid leak.

1996: Yup - oil and coolant are clean - no signs of miscegenation.
Maine in winter = heat's always on.

Bluebimma: Nope - #2 plug distinctly, but not depressingly oily, #3 plug just like #'s 1 and 4 - normal modern lean burn, no unusual whiteness or cleanness.
I'll take a look at the water movement under the cap at cold start.

Thanks, guys. One question I forgot to ask - manual says you need a special BMW camshaft clamp tool and a special flywheel lock tool to pull the head. Rebuilding BMW motorcycle motors and 911 motors taught me that there are special tools you need, and special tools you'd do better without. Any advice about which of these I need or could easily substitute with some tin foil and baling wire?

I'm gonna jump on the bandwagon and say it's a HG, too.

As far as the tools are concerned. You must have the camshaft locking tool and the flywheel lock. This is the only way to time your valves. I made my own, though and posted the drawings in the knowledge base. I suggest you rig up a rigid chain tensioner, too. One more thing, the head bolts are external torx and you need a socket for that. I have an extra set of head bolts laying around, if you want them cheap. Heck I also have a set of the tools which I had made. I might let you borrow them if you pay shipping and get them back to me.

Where in Maine are you. I'm originally from there. Also my brother owns an auto repair shop there and is know for low prices an high quality if you decide you don't want to tackle this now.

Hi Dave -
I'm in Kennebunkport.
Right now I'm using Pirelli "Winter Carving"s on a set of 6" "bottle cap" rims - they're unidirectional winter tires similar to Hakkepellitas, and not expensive. I'm due for new tires this season, though, as well as replacement of bent rims (do these things bend for everyone, or am I just an animal?).

Eric I edited my post since I noticed you asked another question while I was typing.

Here is the link to the tools:
http://www.318ti.org/forum/showthread.php?t=11334

And I do have a set of the special tools you could borrow. I am not sure if the modified torx socket fits for your head. M44's have rocker arms and M42's (like mine) don't.

By the way my brothers shop is in South Portland if you decide you'd rather have it done for you.

Dave,
Thanks.
Those are nice drawings.
I usually shy away from having others do work on my cars, but I will think about it.
I may take you up on the offer of the tools, though, depending on whether it seems like I can limp along with this problem until spring, when I can go out and play.
If my father in law hadn't got the idea twenty-five years ago to replace the barn door with a bay window, I'd have it up on jacks indoors right now...

Just looking at the compression readings I'm tempted to say you're problem is limited to cylinder #2 and I would exclude the head gasket as you usually get low readings on adjacent cylinders (#1, #3 and #4 appear to be ok). Since you said plug #2 is just oily, I would say you might end up having two unrelated problems: you might need a valve job and you have a leak in the coolant system. But that could be just a swag (Scientific Wild Ass Guess)...

For the special tool, you can check with Baum Tools

If you want to exclude the contamination of oil and coolant all together, I would recommend getting a sample of oil and send it out to Blackstone

When i did my headgasket on the m50, i had everything nice and lined up, but in the end, when you torque down the tensioners, it throws cam timing off a smidge, id invest in borrowing or buying cam locking tools.

From the compression results though, i still stick with the possibility of headgasket. The same happened to mine. Most headgasket jobs ive seen with the m4 and m5 series engines usually blown the two center cylinders. 170 isnt bad, but 190 and 180 kinda make it look bad...to me at least.

I am having the exact same problem. plenty of fluid, no heat, car heats up quickly to the red, but strangly after a few miles of hwy driving it normalizes. I had the water pump change last year after the plastic impellor broke. Just change themostat and bled the system. Back to no heat and overheating car. Let me know what you discover.

How many times have you let it overheat, for how long, and to what degree temperature (based on the analog dial in the cluster)?

From the sounds of it, it hasnt been bled correctly and/or thoroughly.

Eric,
I agree that you have a HG problem.
Anyway the only other opinion here is a valve problem which would also entail taking the head off. In my experience, you can definitely have a HG problem and have normal compression on 3 cylinders. It depends where the leak is going. Very likely it's going to your cooling system.
So take the head off and repair it. I would also check the head for flatness, replace the valve seals... maybe guides, too if they are bad. Let a machine shop do that for you. My offer still stands on borrowing the tools.
-Dave

Any chance it could be the heater core? Did you look on the passenger side floorboard to see if there is coolant puddling under the carpet?